This invention relates to elongated mechanical fastening devices such as bolts, screws, rivets, and the like provided with chemically based self-locking means and disposed in a uniform array amenable to robotic handling.
Various fastening devices have been proposed or used utilizing bonding agents in one way or another to prevent the fasteners from loosening during use or service. Ideally, such a fastener-locking system should be capable of easy manufacture and should have long term stability prior to utilization. In use, the fastening device should be capable of being readily applied with minimal preparative treatment and without undue increase in the amount of work or input torque necessary to install the fastener. Once installed, the bonding agent should rapidly establish a bond such that substantially increased work or back-off torque is required to remove the fastener.
In automated assembly systems utilizing robotic equipment to install fasteners, it is necessary that the fasteners be presented to the robotic equipment in a predictably uniform manner. When bonding agents are used as a component of a self-locking fastener system, the bonding agent must be disposed in a manner such that it will not transfer to and thereby contaminate the robotic apparatus.
U.S. Pat. No. 2,901,099 to Krieble discloses a package containing fasteners and a frangible compartment within the package containing a liquid resin capable of curing to a solid after several hours following contact with the fasteners. In use, the compartment is broken, and its contents are mixed with the fasteners. Because of the random arrangement of the fasteners and the uncertain amount and distribution of bonding agent on each fastener, robotic handling cannot be utilized.
U.S. Pat. No. 3,746,068 to Deckert concerns bolts and screws whose threading contains a tack-free composition of a partially micro encapsulated two-component epoxy adhesive system, permitting the fasteners to be shipped and stored in random array. The shearing forces encountered during installation of the fasteners fracture the capsules to activate the adhesive system.
U.S. Pat. No. 4,425,065 to Sweeney discloses a specially designed fastener device confining a sealed container of adhesive which is ruptured to secure the fastener to a substrate.
U.S. Pat. No. 2,666,354 to Dim et al concerns the use of a donut-shaped container of liquid glue utilized as a washer in conjunction with a wood screw. During installation of the screw, the container ruptures to dispense glue into the hole being entered by the screw.
U.S. Pat. No. 3,913,733 to Flesch, et al, discloses the anchoring of fasteners within smooth bore holes utilizing a two component adhesive intermixed from frangible ampoules during insertion of the fastener into the hole.
It is accordingly an object of the invention to provide an assembly of a multitude of self-locking fasteners in a format amenable to use with robotic equipment for handling said fasteners.
It is a further object of this invention to provide an assembly of the foregoing object wherein individual fasteners may be utilized without affecting subsequent utilization of adjacent fasteners.
It is a still further object of this invention to provide an assembly of the aforesaid nature affording greater ease of use by craftsmen.
It is another object of this invention to provide an assembly of the aforesaid nature wherein said self-locking effect is achieved by way of a storage-stable curable liquid bonding agent stored in association with each fastener.
It is still another object of the invention to provide an assembly of the aforesaid nature wherein a constant amount of said bonding agent is applied to the shank portion of each fastener at the time of its use.
It is a yet another object of the present invention to provide an assembly of the aforesaid nature wherein the liquid bonding agent performs a lubricating function during insertive application of the fastener, and then cures to a solid, whereby the fastener is held in place by mechanical and adhesive forces.
These objects and other objects and advantages of the invention will be apparent from the following description.